Pros, cons and conclusion to follow. Hyperlanes is a refreshing supplement to bring science fiction gameplay to Dungeons & Dragons Fifth Edition. It relies heavily on you/your group having knowledge of 5e rules and mechanics, but that's the point (I've seen several reviews that seemed surprised by this.) If you're looking for an inventive approach to creating completely unique sci-fi races and adding some unique backgrounds or magical/technological items to your game, this is not a bad option. (I purchased the PDF/Hardcover combo pack - unless noted, this review can apply to both.)

Pros:

• The sci-fi race creation system is unlike anything else in D&D 5e. Adding the element of the cultural archetype and layering that on top of a bevy of potential sci-fi races is a neat way to customize the character creation process with little extra work.
• The classes presented in Hyperlanes are like the best parts of the Star Wars RPG by Fantasy Flight Games, but without much of the crunch that makes that system cumbersome. Anyone looking to run a Star Wars-themed game in D&D would do well to start here.
• Gambits (this supplement's version of spells) are a great concept that bridges the gap between the thousand feats of Starfinder with a 5e system that can leave some classes with many fewer neat tricks. What an elegant way to solve that problem!
• The technology and supertech (magical items) in the guide are fun and inventive with lots of options that put roleplay on even footing with mechanical advantage.
• The art is incredible - in fact, one of my favorite things about the book. It inspires adventure in me!

Cons:

• The ship combat system is sorely lacking. Any players engaging in a sci-fi game are looking for a ship combat system that is comprehensive but easy to learn - I don't find this system to be either. The layouts of ship stat blocks are also confusing and hard to use. When creating a supplement to D&D 5e, your layouts certainly do not have to mirror D&D books to the tee - but they should seem familiar, and these did not.
• Ditto the creatures that are listed in the back of the book. Creating a basic monster stat block is a pretty simple task (I do it in Google Docs for my home game almost every week) and Hyperlanes does not succeed on this count.
• These classes would probably work better as subclasses. Rather than presenting a class with a wink-and-a-nudge and an understanding that it's actually this other class you're familiar with - just say "these Ambassador-themed subclasses are for the Bard class," etc. This book already concedes that you'll need the D&D 5e books to get the most of it, so why not lean into that portion of it?
• I like the gambits, but I wish the classes didn't eliminate D&D 5e spells completely. It would not be hard to present the gambits as a special kind of spell that uses those mechanics, since that's what it does, anyway.
• The layout of the PDF/book verges on amateurish. This partially ties into my point about stat blocks for monsters/ships, but is also present in much of the text. It lacks polish.
• Overall, I think this product feels like a beta-test version of a supplement. The system is sort-of half-baked and the content just doesn't seem to be in its final iteration, like neat homebrew content that I might buy when I want new backgrounds here or a new magic item there, but not cohesive. I know when I buy from independent creators that it will not have all the polish of an official RPG book, but - especially when buying a hardcover book of it - I do expect something a little more refined.

Conclusion: Hyperlanes is fun and inspiring and would make a good addition to your bookshelf if you're looking to run a science fantasy game for D&D 5e or add some anachronistic pieces to your bog-standard D&D game, but it is not the comprehensive system that you're looking for. I will definitely borrow things from it for an upcoming science fantasy game - and will gladly allow my players to pick certain things from it to complement their character builds - but this alone does not a sci-fi game make.